Synthesis and structural characterization of lithium and sodium complexes of 5-ethylamino-4-methyl-1,2-benzoquinone 2-oxime

Abstract Reactions of 5-ethylamino-4-methyl-1,2,benzoquinone 2-oxime (5-Et-4-MeqoH) with lithium and sodium hydroxide produce a series of complexes of types [M(5-Et-4-Meqo)(5-Et-4-MeqoH) n ] [ n = 0, 1 when M = Na; n = 1, 2 when M = Li]. All the compounds in this series have been characterized by elemental and spectroscopic analyses and the solid state structures of the complexes [Na(5-Et-4-Meqo)(5-Et-4-MeqoH)(H 2 O) ∗d H 2 O] and [Li(5-Et-4-Meqo)(5-Et-4-Meqo-H) 2 ∗d 1 1 2 H 2 O ] have been determined by a single-crystal X-ray diffraction analysis. In both the compounds, conjugation involving the atoms N(7)C(4)(3)C(2)O(2) is observed, thus supporting the ligand configuration as being an intermediate between the quinone oxime and imino oxime form. The 1 H NMR spectra of the tris-chelate [Li(5-Et-4-MeqoH)(5-Et-4-MeqoH) 2 ∗d 1 2 H 2 O ] and the bis-chelate [Na(5-Et-4-Meqo)(5-Et-4-MeqoH)(H 2 O) ∗d H 2 O] are consistent with the solid state structures and establish that, even in solution, the coordination generated around the metal ion remains unaltered.